EXPERIMENTAL HIGH ENERGY PHYSICS

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EXPERIMENTAL HIGH ENERGY PHYSICS DEMOKRITOS
CMS/LHC PRESHOWER PROJECT

• Overview
• Activities
• Detector Construction
• Physics Tools
• Infrastructure
• Detector Instrumentation
• Publications
• Education
• Personnel

Dr. Aristotelis Kyriakis On behalf of Demokritos
HEP group
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DEMOKRITOS CMS/LHC PRESHOWER PROJECT Overview
Neutral pions (p0) created in the LHC decay into
2 closely spaced photons. These pions form an
important background to the Higgs decay H ? ??
particularly in the endcaps (1.65lt?lt2.6). The
CMS preshower detector is a self contained
compact system comprising two orthogonal planes
of silicon strip sensors, each preceded by a
layer of lead (to initiate electromagnet
showers). The silicon detectors are equipped with
pulse-height readout to enable differentiation
between energy deposits from single or double
photons coming from a p0.
The preshower project is a joint effort of
collaborators from Armenia(Yerevan P.I.),
Belarus(U. of Minsk), CERN, Greece(NCSR
Demokritos, U. of Ioannina), (india(BARC, U. od
Delhi, (Russia(JINR Dubna) and Taiwan(NTU, NCU)
The preshower will utilize more than 4300 silicon
sensors totaling around 16m2. Each sensor has
dimensions 63mm x 63mm x 320µm and is segmented
in 32 strips measuring 1.9mm x 61 mm x 320µm. The
active planes of the preshower detector are built
from identical "micromodules", each of which
contains an individual sensor and read out
electronics.
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DEMOKRITOS CMS/LHC PRESHOWER PROJECT
Activities(Detector Construction)
The Preshower group of the Insitute of Nuclear
Physics has contributed to the design and
development of the silicon sensors and the very
front analog readout electronics. The group has
taken the responsiilities to the assembly, test
and installation of around 500 micromodules and
the development of data reduction algorithms
aiming the discrimination of neutral pions from
single photons.
Design and development of silicon sensors was a
five years joint effort of the Institutes of
Nuclear Physics and the Institute of
Microelectronics, both working within NCSR
DEMOKRITOS. At the end of the project, a number
of 50 final sensors were produced and the
specifications are provided to commercial
partners for mass production.
A prototype in submicron technology (0.25 µm) of
the frond end chip of the Preshower detector was
designed by the two Institutes of DEMOKRITOS in
collaboration with CERN
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DEMOKRITOS CMS/LHC PRESHOWER PROJECT Activities(De
tector Construction)

• Demokritos is committed to the construction of
  500 micromodules
• 516 silicon sensors are available and already
  tested
• 50 from the Institute of
  Microelectronics
• 40 from Russia (ELMA)
• 426 from Hammamatsu
• Hybrids and Tiles in the way of fabrication
• VLSI electronics finalized

Micromodule Layout
Intensive construction of micromodules is
foreseen for the first semester of 2005
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DEMOKRITOS CMS/LHC PRESHOWER PROJECT Infrastructur
e

• Laboratory (80 m2 ) with temperature and
  humidity
• control

• Probe Station Carl Suss PA 150
• CV HP4092A
• IV Keihley 6517

• SMD Placement FRITSCH

Wire Bonding (Delvotec 5430)
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DEMOKRITOS CMS/LHC PRESHOWER PROJECT Activities(An
alysis Tools)

• p0 - ? separation

p0 from jets Pt spectrum
Full CMS Detector Simulation
A Neural Network (NN) is used to distinguish
single photons (from decays of an intermediate
mass Higgs) from double photons (from the decay
of p0s). Keeping 90 of the single photons, the
NN rejects more the 50 of the p0s. The algorithm
is applied for the unconverted photons while for
the converted before reaching the Preshower a
different procedure is under development using
combined information from tracker, Preshower and
Electromagnetic Calorimeter .
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DEMOKRITOS CMS/LHC PRESHOWER PROJECT
Detector Instrumentation
A fast single photon counting system is
developed for X-rays applications (XRD, baggage
inspection system) as a byproduct of the
Preshower VLSI electronics
It includes two ASICs and a DAQ system that
constitutes a fully operational system
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DEMOKRITOS CMS/LHC PRESHOWER PROJECT
Publications (2000-2004)

• Publications in reviewed articles(Combined
  CMS/LHC Preshower Detector Instrumentation)
• Nucl. Instr. and Meth. A 7 , IEEE Trans. Nucl.
  Sci. 2
• CMS/LHC Notes 2
• Presentations in International Conferences
  Workshops 5

• Talks in CMS/LHC Collaboration 10

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DEMOKRITOS CMS/LHC PRESHOWER PROJECT
Educational Activities

• Ph.D Degrees Two completed ( One in
  H.E.P., One in Electronics)
• One in progress
• 10 Students from the Technological Educational
  Institutes of Greece (TEI) elaborated the
  Industrial Training Period (6 months) in the
  Laboratory
• Spin Off Companies Athena Semiconductors(www.ath
  enasemi.com)
• (N. Haralabidis, S. Kavadias) specialized in
  VLSI electronics

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DEMOKRITOS CMS/LHC PRESHOWER PROJECT
Personnel
Senior scientists 4 (M.
Barone, A. Kyriakis, D.Loukas, A.Markou) Post
docs 1 (G. Anagnostou ) Associate
Researcher 1 (K. Karafasoulis) Ph.D.
Students 2 (Ch. Mavromatis, G.
Vermisoglou) Permanent technicians
1 (E. Saragas) On contract technicians 2
For more than ten years the group is following a
research policy aiming at the formation of an
interdisciplinary group of RD in the field of
solid state detectors and related readout VLSI
electronics. This activity resulted in joint
projects with other institutes of the NCSR
DEMOKRITOS (Institutes of Microelectronics
Materials Science). Electronics engineers have
been working for many years on a contractual
base. No possibility to offer to some of them a
permanent post. Finally they left for the
industrial sector resulting in a discontinuity
for the relevant activities.
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DEMOKRITOS CMS/LHC CASTOR
CASTOR is an Electromagnetic/Hadronic calorimeter
conceived and proposed for Heavy Ion Physics
Program at the LHC It is designed for potential
discovery of New Physics such as Centauros,
Strangelets in addition to bread butter
Physics
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DEMOKRITOS CMS/LHC CASTOR
The passage of a strangelet through the sectors
of the CASTOR produces a transition curve with
many, slow attenuated maxima, extended to the end
and beyond The passage of many (20) hadrons on
the other hand with a distribution in energy
produces a smooth transition curve, rapidly
attenuated
Strangelet signal
In NORMAL PbPb central collision(Etot 1144
TeV) the expected Energy/sector will be ESECTOR
15-60TeV ? Sector with Strangelet ESECTOR
10TeV ? Sector without Strangelet
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DEMOKRITOS CMS/LHC CASTOR
A tool to measure pp Luminosity via the QED
process pp ? pp ee- The electrons of the above
process are in very forward range (polar angles
of a few mrads) The x-section of the above
process is µbarns ? gives high rates of a few
kHz Can measure Luminosity with an error of the
order of 1-2 much better of the error of gt5
taken using leptonic Z,W production
The conceptual idea and design of CASTOR is a
collaborative work of Athens University,
Univerity of Ioannina and Demokritos (Dr. Costas
Kalfas)
Demokritos is involved in data acquisition and
analysis from test runs and the comparison with
the simulated data
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DEMOKRITOS CMS/LHC PHYSICS
RESPOSIBILITIES IN THE FRAMEWORK OF THE CMS/LHC
PHYSICS TECHNICAL DESIGN REPORT(P-TDR)

• FCNC decays of top in CMS
• SUSY search in c20 ? Z0 c10 decays
• Search for T?tZ,Wb of Littlest Higgs Model in CMS
• MSSM Higgs in the channel ?-gt?h,Z-gtll, h-gtbb

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FCNC decays of top in CMS
The Flavor Changing Neutral Current (FCNC) decays
of the top quark t ? qV (V g, ?, Z) that occur
at one loop are suppressed in SM by a factor
mb2/MW2 in the amplitude In SM their expected BR
is very small (of the order of 10-11 to 10-13)
Significant increase in their BR ( by several
orders of magnitude) are predicted in SUSY
extensions of the SM Especially in R-parity
violating MSSM with existing bounds on R-parity
violating couplings, that violate the Baryon
number, the BR of FCNC of t decays might reach
to a detectable level in LHC Any observation at
the LHC would be a signal of new Physics
Will NOT be studied due to the large QCD
background
Background Sources ttbar, EW top, Wjets, W?,
ZZ, ZW
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FCNC decays of top in CMS
Analysis performed for the t?q?(q u,c) channel
in fast and full CMS detector simulation
Signal
Fast Detector Simulation
L 10fb-1
A BR of the order of 10-4 can be calculated
assuming 5s signal significance at an integrated
luminosity of 10fb-1
Work in progress to study full detector
simulation background events and the other top
FCNC decays as well. Systematics from b-tagging,
lepton and jet callibration is also an important
task
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SUSY search in c20 ? Z0 c10 decays

• Phenomenological implications of SUSY are
• model dependent. Discovery potential is
  studied
• considering the minimal supergravity
  (mSUGRA)
• constrained model few (5) extra free
  parameters.
• CMS collaboration has chosen several
• Benchmark points to test SUSY
• Low Mass (LM) for SUSY discovery quickly
• after LHC startup
• Diversity of final states in order to cover
  various
• experimental signatures.
• Points beyond Tevatron reach
• Keeping in mind LEP exclusions
• Point LM4 m0210 GeV m1/2285 Gev
  tan(b)10 mgt0 A00

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SUSY search in c20 ? Z0 c10 decays

• Signal c20 ? Z0 c10
• topology e e-, mm- (b.r. 6,7)
  missing Et
• Backgrounds susy background, ZZ, ZW, WW, Zbb,
  ttbar, bbar
• generator level study of signal and some
  background done
• 
  
• To be done
• Production of signal at CERN and locally with
  full detector simulation .
• Analysis at Demokritos to evaluate the
  sensitivity to this SUSY topology
• Fast simulation for other mSUGRA parameters to
  explore the SUSY discovery capability through
  this channel

Missing Et after preliminary cuts on Pt of final
state leptons and on invariant mass of same
flavor opposite sign lepton pairs
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Search for T?tZ,Wb of Littlest Higgs Model in CMS

• The Higgs mass in the SM is quadratically
  sensitive to the cutoff scale ? of the SM
  effective theory via radiative corrections. There
  should be a way to cancel out these corrections
  in order to have the naturalness of a light Higgs
  boson
• The classical solution is Supersymmetric theories
  that introduce an extended space-time symmetry
  between the bosonic and fermionic partners. The
  quadratic divergences in the Higgs mass due to
  top quark, gauge boson and Higgs loop are
  cancelled by top squark, gaugino and Higgsino
  loops, respectively, while the Higgs mass should
  be O(1 1TeV).

• The Little Higgs models are an alternative way to
  keep the Higgs boson naturally light and the
  quadratic divergences in the Higgs mass are
  canceled at the one loop level by new particles
  of the same statistics with masses M ? 1-3 TeV

A specific realization of the little Higgs idea
is the Littlest Higgs model in which the
cancellation of the top-quark loop terms is
performed by requiring a colored vector-like
particle noted as T.
Our goal is to test the discovery potential of
the T quark in the CMS/LHC environment, for
various T quark masses
The x-section depends on the Yukava couplings of
the new T quark ?1 and ?2.
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Search for T?tZ,Wb of Littlest Higgs Model in CMS

• The decays of T are the following
• i) T ? tZ with BR 25
• ii) T ? Wb with BR 50
• iii) T ? tH with BR 25
• Cases (i) and (ii) will be of our interest and
  we ll restrict ourselves in the leptonic decays
  of Z0, W bosons

Fast Detector Simulation
T ? tZ
Background Sources ttbar, EW top, ZZ, ZW, Wbbar
High luminosity channels First Results from fast
detector simulation show that for T ? tZ 12
events expected at L 300fb-1 with very low
background
Work in progress to study full detector
simulation signal and background events taking
into account pileups, and systematics from
b-tagging, lepton and jet callibration
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MSSM Higgs in the channel ?-gt?h,Z-gtll, h-gtbb

• This channel concerns the CP-odd pseudoscalar
  Higgs (A) through its decay to Z0 and the
  lighter CP-even Higgs (h) pp ? A ? Zh . The
  maximum BR(A?Zh) is in the low tan? MzMh ?
  MA?2Mtop. The final state is Z0?e e-, ? ?- and
  h?bb which allows simultaneous detection of ?, h
  higgs bosons.
• NLO estimations for cross-sections the
  branching ratios (with the tools HIGLU, HDECAY)
  and kinematics with PYTHIA. The most important
  bkg processes Zbb, ttbar, Zjets,ZZ, ZW are
  available . Next steps signal significance
  estimations in bins of MA tan? for Mhmax
  senario, reconstruction of M? Mh, study of
  systematics.

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DEMOKRITOS CMS/LHC PHYSICS Personnel
Senior scientists 5
(T.Geralis, A. Kyriakis, D.Loukas, A.Markou,
C.Markou) Post docs 2 (G. Anagnostou, S.
Kyriazopoulou ) Associate Researcher 2 (K.
Karafasoulis, K. Zachariadou) Ph.D. Students 2
(Ch. Mavromatis, G. Vermisoglou)